Mortgage payoff planning
Mortgage Extra Payment Calculator
Compare your current mortgage schedule with monthly extra principal, an annual extra payment, and a one-time lump sum.
Results will appear after valid values are entered.
Compare the remaining interest
Extra principal reduces the balance used to calculate later interest. The scheduled principal-and-interest payment continues under this calculator’s assumptions.
Year-by-year balance comparison
The table compares the estimated remaining balance at each year-end. Interest saved is cumulative through the displayed month.
| Time | Without extras | With extras | Interest saved |
|---|---|---|---|
| Enter valid values to build the schedule. | |||
How this mortgage calculator works
When the monthly principal-and-interest field is blank, the calculator estimates the fixed payment required to amortize the current balance over the remaining term. An entered payment overrides that calculated amount.
Current balance × annual rate ÷ 12
Regular interest - accelerated interest
Monthly extra principal is applied after the scheduled payment. The annual extra amount is applied every 12 months. The one-time lump sum is applied after the selected month’s scheduled and monthly extra payments.
The calculator assumes a fixed interest rate, monthly interest, no missed payments, and no change to the required payment after extra principal is applied. It does not model adjustable-rate changes, recasting, refinancing, escrow, daily-interest differences, payment-processing delays, or prepayment penalties.
Confirm with the mortgage servicer that extra amounts will be applied to principal and review the loan terms before making a large payment.
For educational purposes only. Results are estimates and may differ from the servicer’s amortization schedule because of payment dates, rounding, daily-interest methods, fees, escrow, loan terms, and how extra payments are applied. Review the Calculator Methodology for shared assumptions, rounding, payoff timing, and privacy-conscious analytics details.